Упр.181 Вариант 3 Дидактические материалы ГДЗ Мерзляк Полонский 6 класс (Математика)

1) -27 + 68 — 56 + 61;
2) 4,17 — 9,42 + 0,2;
3) 3,1 + (-4,72) + (-8,12) — (-0,96);
4) -18,31 — 6,27 + (-8,44) — (-31,67);
5) 6 5/12 — (-4 2/3) + (-2 3/4);
6) 4 1/8 — 6 2/9 + (-3 1/6) — (-5 3/4).

1) $$-27+68-56+61=(68-27)+(61-56)=41+5=46.$$

2) $$4{,}17-9{,}42+0{,}2=(4{,}17+0{,}2)-9{,}42=4{,}37-9{,}42=-5{,}05.$$

3) $$3{,}1+(-4{,}72)+(-8{,}12)-(-0{,}96)=3{,}1-4{,}72-8{,}12+0{,}96$$
$$=(3{,}1+0{,}96)+(-4{,}72-8{,}12)=4{,}06-12{,}84=-8{,}78.$$

4) $$-18{,}31-6{,}27+(-8{,}44)-(-31{,}67)=-18{,}31-6{,}27-8{,}44+31{,}67$$
$$=(-18{,}31-8{,}44)+(31{,}67-6{,}27)=-26{,}75+25{,}4=-1{,}35.$$

5) $$6\frac{5}{12}-\left(-4\frac{2}{3}\right)+\left(-2\frac{3}{4}\right)=6\frac{5}{12}+4\frac{2}{3}-2\frac{3}{4}$$
$$=6\frac{5}{12}+4\frac{8}{12}-2\frac{9}{12}=10\frac{13}{12}-2\frac{9}{12}$$
$$=8\frac{4}{12}=8\frac{1}{3}.$$

6) $$4\frac{1}{8}-6\frac{2}{9}+\left(-3\frac{1}{6}\right)-\left(-5\frac{3}{4}\right)=4\frac{1}{8}-6\frac{2}{9}-3\frac{1}{6}+5\frac{3}{4}$$
$$=4\frac{9}{72}-6\frac{16}{72}-3\frac{12}{72}+5\frac{54}{72}$$
$$=(-2)\frac{19}{72}-3\frac{12}{72}+5\frac{54}{72}=-5\frac{31}{72}+5\frac{54}{72}=\frac{35}{72}.$$

Ответ

1) 46; 2) $$-5{,}05$$; 3) $$-8{,}78$$; 4) $$-1{,}35$$; 5) $$8\frac{1}{3}$$; 6) $$\frac{35}{72}$$.